U.S. Pat. No. 4,850,197, which is assigned to the same assignee as the present application, discloses a vapor compression refrigeration system based on an economizer cycle which utilizes a refrigerant compressor having an intermediate pressure port, in addition to suction and discharge ports. An economizer heat exchanger is used to enhance hot gas cooling and heating cycles which are initiated by associated electrical or electronic control to achieve and maintain a predetermined temperature range close to a selected set point temperature in a served space to be conditioned.
U.S. Pat. No. 5,174,123, issued Dec. 29, 1992 entitled Methods and Apparatus for Operating a Refrigeration System, which is assigned to the same assignee as the present application, discloses refrigeration methods and apparatus which utilize a flash tank in a refrigeration system which has an economizer cycle, in place of an economizer heat exchanger. The refrigeration arrangement disclosed in the aforesaid application eliminates the need for a float valve in the flash tank, enabling the flash tank to be used in transport refrigeration applications.
It would be desirable, and it is an object of the present application, to improve the reliability and efficiency, as well as the control methods and arrangements, of refrigeration systems which have an economizer cycle, such as the refrigeration systems disclosed in the hereinbefore mentioned patent and patent application.